1. Field of the Invention
The present invention relates to a belt for use as a transfer member in an electrophotographic process, that is, a transfer belt, and a full color image-forming apparatus equipped with the transfer belt.
2. Description of the Related Art
With respect to image-forming apparatuses using an electrophotographic process, those which use an intermediate transfer system have been well known. In the intermediate transfer system, after having applied a constant charge onto a latent-image-supporting member made of a photosensitive member, an electrostatic latent image is formed thereon through a laser and the like, and the image is developed by using charged toner. Next, after the toner image on the latent-image-supporting member has been primary-transferred on a transfer belt, the toner image is further secondary-transferred onto a sheet of recording paper. In such an intermediate transfer system, it is necessary to maintain a uniform resistance distribution on the transfer belt in order to achieve high image quality.
The transfer belt is composed of resin in which a conductive substance such as carbon black is dispersed, and an attempt has been made to achieve a uniform resistance distribution on the transfer belt by properly dispersing the conductive substance therein. However, since the dispersing property of the conductive substance such as carbon black is generally low, at present, it is difficult to obtain a uniform resistance distribution.
For example, a method has been proposed in which the specific gravity of the resin of the transfer belt and the specific gravity of the conductive substance are made approximate with each other (U.S. Pat. No. 6,139,784); however, the dispersion of the conductive substance, in particular, carbon black, is still insufficient, failing to achieve a uniform resistance distribution.
Moreover, for example, a method using acidic carbon has been proposed (U.S. Pat. No. 6,751,434); however, although this method improves the dispersing property of carbon black, it becomes difficult to control the conductivity since the amount of use of carbon black is limited.